Conventional internal combustion engines are provided with a number of different operating mechanisms for controlling or operating inlet and outlet valves for the engine cylinders or in the case of fuel injected engines for controlling the injectors. Usually such mechanisms take the form of cam shafts, rockers, return springs or other mechanical actuating elements. Such mechanism suffer a number of disadvantages and limitations including in the case of valved engines, poor valve cooling, poor lubrication, a lack of ability to maintain alignment of the valves with their seats, poor control over movement of the valve and an excessive amount of power which is required to overcome the valve seating springs.
Particular disadvantages associated with fuel injectors include lack of flexibility of injection timing, excessive mechanical components in the injector drive train, an excessive amount of power wastage in operating the injectors and their drive train and a lack of ease of assembly and removability of the injectors and associated drive train from the engine during maintenance.
In my International Patent application No. PCT/AU90/00387, I describe hydraulically operated fuel injectors and valves for internal combustion engines wherein an actuator which incorporates dual pistons includes an internal axially extending slide valve for controlling operation of the actuator.
It has been found in practice that the function and control of the above hydraulically actuated fuel injectors and valves has been limited by the excessive stroke length of the control valve causing in the case of fuel injectors an inadequate rate of fuel injection or quantity of fuel injected or in the case of valves inadequate rate of opening or closing of the valve. In addition, there is no readily accessible means for adjusting stroke length for fine adjustment or an efficient means for addressing the problems of component wear. A further disadvantage is that there is no method of addressing the abrupt cessation of motion at stroke end.
In hydraulically operated valves, the above disadvantages lead to a limitation in the number of operational cycles per second and thus the operational speed of the engine.
In my International Patent Application No. PCT/AU90/00387, I also describe an hydraulically operated reciprocating internal combustion engine wherein an hydraulic actuator is coupled to an engine piston arranged for reciprocation within a cylinder to move with or cause reciprocation of the engine piston. The hydraulic actuator includes a number of chamber sections as well as a discharge or vent chamber adjacent to the engine piston through which hydraulic fluid is vented. It has been found in practise that the length of the combined cylinder unit of such engines is unreasonably long and that the discharge of fluid from the vent chamber is inefficient.